He had been guarding the U.S. Embassy in Ankara , as he 'd done many other days -- with commitment and professionalism . She had gone there to have tea with the ambassador , a respected television journalist set to renew acquaintances with a diplomat and do her job .

Then came the blast .

Whether or not they 'd crossed paths before , these two people 's stories now forever will be intertwined -- thanks to a man Turkish authorities say belonged to the Marxist Leninist organization known as the Revolutionary People 's Liberation Party , or DHKP-C , which the U.S. government and others label a terrorist organization .

What is the DHKP-C ?

Ecevit Sanli , as he was identified by Istanbul police , died after detonating his bomb near the embassy 's Gate No. 2 around 1:15 p.m. -LRB- 6:15 a.m. ET -RRB- Friday .

So , too , did the Turkish guard -- described by U.S. Ambassador Francis Ricciardone as a `` hero , '' and identified by Turkey 's semi-official Anadolu News Agency as Mustafa Akarsu .

A photo showed the journalist being carried away on a stretcher , apparently bleeding . Rather than sitting with her for tea , Ricciardone visited the woman -- Didem Tuncay -- at Ankara 's Numune Hospital , and afterward described her as `` one of the best . ''

While theories have been floated , neither Turkish nor U.S. authorities have detailed why they think Sanli blew himself up . Prior to Friday , he was known to U.S. and other intelligence agencies , a U.S. law enforcement source told CNN .

Whatever Sanli 's rationale , the explosion spurred security clampdowns at diplomatic facilities in Turkey , plus messages of condolences and solidarity . Turkish Prime Minster Recep Tayyip Erdogan called it an attack `` against the peace and welfare of our country . ''

Yet the violence reverberated well beyond Turkey 's borders , however , especially in the nation whose embassy was targeted .

The spotlight on U.S. diplomatic installations was already intense after violence last September in Egypt , Tunisia and Libya , where Ambassador Christopher Stevens was one of four Americans killed in Benghazi .

U.S. Rep. Ed Royce said Friday 's explosion in Turkey served as `` yet another stark reminder of the constant terrorist threat against U.S. facilities , personnel and interests aboard . ''

`` Coming after Benghazi , it underscores the need for a comprehensive review of security at our diplomatic posts , '' said Royce , a California Republican and chairman of House Foreign Affairs Committee .

` He exploded at the guard '

The bomber had first gone to the rear access of the embassy , then went to a checkpoint on the building 's perimeter where IDs are checked , explained U.S. State Department spokeswoman Victoria Nuland . According to law enforcement sources working on the investigation , Sanli blew himself up on a walkway for embassy employees and their guests .

`` He exploded at the guard , '' Nuland explained .

The guard , Akarsu , on one side of the security barrier was killed . Two guards on the other side of the glass survived , said the State Department spokeswoman .

The blast blew a hole in what appeared to be a building that is part of the compound 's outer gate , images from CNN sister network CNN Turk showed . This was all part of a large complex that includes blast doors , reinforced windows and a series of metal detectors that visitors must navigate before reaching embassy offices .

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The attack stirred swift condemnations , as well as fresh security precautions . The U.S. Embassy in Ankara subsequently put out a statement telling Americans not to visit that facility or U.S. consulates in Istanbul or Adana `` until further notice . ''

Portions of Paris Avenue , where the targeted embassy is located , were shut down , according to Anadolu news . Germany and France , meanwhile , were among the countries who tightened their security in the wake of the blast .

The U.S. ambassador said in a statement that he 'd `` paid my respects to the family of the Turkish hero who stood guard for us every day . ''

Calling him `` well trained -LRB- and -RRB- committed to his job , '' Ricciardone praised the late guard as a `` good , excellent , professional guard '' who `` died defending the Turks and the Americans who work at the embassy . ''

The ambassador also talked about visiting Tuncay , whom he recalled was `` the first person to interview me when I arrived two years ago at NTV . '' Having learned she 'd recently left the Turkish network , Ricciardone said he invited her to tea .

`` She serves her country by getting the truth to the Turkish people , '' the ambassador said . `` She , I think , is one of the best . ''

Not first brush with terror for Turkey , U.S.

Friday 's blast was hardly Turkey 's first brush with terror .

At the nexus of Europe and Asia , and with deep roots in the Muslim and Christian spheres , Turkey has long been a boiling pot -- and , occasionally , a target .

In recent years , it has been site of many acts of political violence from groups such as leftist anarchists , Kurdish separatists , Islamists and al Qaeda .

Hasan Selim Ozertem , a security expert at the International Strategic Research Organization in Ankara , said Friday 's attack could be related to recent arrests of DHKP-C members .

Since the beginning of January , 85 members of the group have been taken into custody , he said , adding that Turkish police have been closely focusing on the group over the past five years . The DHKP-C was established in the 1970s .

Ozertem said that one plausible theory is the group is trying to send a message to Turkish authorities by attacking the U.S. Embassy because it is near the Turkish parliament building .

DHKP-C has a track record as a `` subcontractor '' group for other militant outfits , and it is also believed to have relationships with states in the region such as Syria and Iran , Ozertem said .

The group has a relationship with the PKK , the Kurdistan Workers Party , which has been at odds with Turkey 's government for some time . Ozertem said the attack could be linked to negotiations between the PKK and Turkish government .

Another possibility is that Syria or Iran could be involved , considering the recent deployment of Patriot missiles in Turkey as a defense against possible missiles from Syria .

The explosion occurred as about 400 U.S. military personnel are moving Patriot missile defense equipment to a Turkish base as part of an effort to defend the country from possible attack from Syria . The first battery became operational last Saturday in the city of Adana , NATO said , and more equipment arrived Wednesday in the port city of Iskenderun .

Erdogan , however , ruled out that Friday 's attack had anything to do with Syria , according to an interview on the private Habertuk channel later reported by Andolu .

Of course , this may have to do primarily with the United States itself -- independent of anything involving Turkey or its government .

While the U.S. Embassy in Ankara has not seen this kind of incident in decades , in 2008 three police officers died in a shootout with assailants outside the U.S. Consulate in Istanbul .

Three attackers died in the incident , which the U.S. ambassador at the time called `` an obvious act of terrorism . '' One of the attackers in that incident was believed to have trained with al Qaeda in Pakistan 's Waziristan region .

Read more at CNN Turk .

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A suicide blast occurs at a checkpoint on the perimeter of the U.S. Embassy in Ankara

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A wounded journalist was going to have tea with the U.S. ambassador , he says

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The ambassador has talked with the family of the `` excellent '' guard killed in the blast

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The bomber , part of a leftist terror group , was known to the U.S. , source says